Condition indicating means for fuses



April 14, 1936. L 5 BRACH v ZQEZOGZ CONDITION INDICATING MEANS FOR FUSESFiled Nov. 18, 1953 2 Sheets-Sheet l eA m 2.391%? ATTORNEY L. S. BRACHCONDITION INDICATING MEANS FOR FUSE IS A ril 14, 1936.

Filed Nov. 18, 1935 2 Sheets-Sheet 2 26 INVENTOR Zeazz 552 2105.

iii/K 5 ATTORN EY Patented Apr. 14, 1936 endear or ies CQNDHTEQNIL'NEDKCATHNG IMANS FUSES lLeon S. Erach, East Grange, N. ii.

application November 1 it! (Claims.

This invention relates to indicating means for showing the operatingcondition of fuses used in electrical circuits.

One of the objects of my invention is to provide a condition indicatingmeans for such fuses which may be incorporated in the structurescarrying said fuses, for example in the fuse-blocks themselves, withoutchanging the outside or mounting dimensions of the fuse-blocks whichhave become standardized to a great extent, whereby the fuseblocks willfit into cabinets designed to take a certain number of the blocks.

Another object of my invention is to provide an indicating means forfuses which does not alter or affect the design and cost of the fuseitself; that is to say, my indicating means is incorporated as apermanent part of the block and not of the fuses, so that the purchase:of fuses is not burdened with the cost of certain indicating means whichhave been heretofore proposed and used as a part or" the fuses per se,or ofiered as an auxiliary.

Another object of my invention is to provide means whereby theindicating means will show the condition of a fuse even though the loadon the circuit in which the fuse is connected be on open circuit.

Another object of my invention is to provide condition indicatingmeansfor fuses which adds but little to the change and cost of thestandardfuse-block, yet one that is highly efficient in operation and has a longlife.

These and other objects will be clear to one skilled in the art to whichmy invention may be applied.

In order to illustrate the application of my invention, I have shown itapplied to several designs of fuse-blocks which are illustrated in theattached drawings, wherein:

Figure 1 is a plan view of a single circuit branch block with myinvention applied thereto for use in connection with fuses of thescrew-plug type.

Figure 2 is a plan view of the bottom of the block shown in Figure 1,illustrating one method of connecting the indicating means to thecircuit terminals.

Figure 3 is a section on the line 3-3 of Figure 1.

Figure 4 is a plan view of another type of block without thecurrent-connecting terminals.

Figure 5 is a bottom view of the block shown in Figure 4, illustratinganother method of connecting the indicating means across the fuses.

Figure 6 is a plan view of a three-way block adapted to receive acartridge type fuse.'

8, i933, Seriai No. @Qdfii ((Cla Ew -3111i) Figure l isa view or" thebottom of the block shown in Figure 6.

, Figure 8 is plan view of a fuse-block cabinet with the door open,showing a block adapted to receive four fuse plugs of the screw-typewith my invention applied thereto.

Figure 9 is a diagram illustrating the method of application ofinvention as well as the means for insuring that. the fuse indicatingmeans will function, eventhough the load circuit be open.

Figure 10 is a diagram showing part of Figure a, but with a condenseradapted to be bridged across the load circuit in place of the resistoroi Figure 9.

Referring now to the details wherein like numbers refer to correspondingparts in the various views, and referring particularly to Figures 1 and2, i is a block oi good insulating material, such as porcelain, havingchannels 2 and 3 therein to receive conductors; which are engaged by thecon- .tactors 3 and 5. Thejblocl: i has moulded integrally therewithcircular shaped barriers 6 and l extending upwardly from the baseportion of the block to form pockets to receive contact members ormetallic shells 3 which are formed with screwthreads thereon to receivea screw-threaded type of fuse plug. The contactors l and 5 extend belowthe pockets in the base of the block as indicated in Figure 3, and arefastened to the block by contact members Ei which may be in the form ofscrews. Each of the shells 8 has outgoing terminals i ii to which theload wires are attached. Thus far, this is the usual construction of afuseblock.

My invention provides openings 8 ll positioned in the barriers G and lor closely adjacent thereto and one edge of each opening ll breaksthrough the barriers or has a passageway l2 opening into the pocketcarrying the shell 8. Positioned within each opening l i is a small lampbulb i3 having spaced electrodes i l and i5 mounted within the bulbwhich is filled with an inert gas such as neon. One of the electrodes,such as M, is connected by a wire it to the shell 8, through thepassageway l2, while the other electrode I5 is connected by a wire ii toa very high impedance H3. The impedance l8 may be in the form of aresistance of the grid-leak type such as used in radio, or a very smallcondenser where fuse-blocks are to be used on alternating currentcircuits. current is used, then the impedance l8 will be in the form ofa very high resistance of the order of fifty thousand to one hundredthousand ohms, or even very much higher. Because of the sensitivity ofthe neon bulb l3, this impedance, which If direct ance and thereby causethe same, particularly if the impedance is of the grid-leak type, toheat up and cause it to flash over a short-circuit, in which case itsometimes happens that the neon lamp will explode. To avoid thiscondition, I may connect another impedance IS in series with theimpedance l8, and then connect the impedance I9 by a conductor 20 to thecontact member forming one side of the fuse circuit. By the use of twosuch impedances I have found that one will give out before the other andno damage is done to the second impedance or to the bulb. As will beseen from Figure 2, the impedances l8 and I 3 are set in a recess in thebase of the block in a similar manner-to the circuit terminal strips 4and 5 and are covered over or protected by the cement or wax which isused in covering the parts 4 and 5 in the base of the block.

In Figures 4 and 5, the construction is somewhat similar to that shownin Figures 1 and 2, but the bulbs l-3 are arranged a little differentlyon the block and likewise the impedances l8 and 19.

The same thing applies to'the type of fuse-block shown in Figures 6 and7. In either of the forms described, the impedances I! and I3, or whereonly one is used, may be made integral with the block itself; that is, amixture of finely pulverized carbon or graphite with a binder may bepainted material used in covering the circuit terminals in the base ofthe blocks as has previously been described.

In Figure 8, a metal casing 32, preferably of steel, has a'door 2| forclosing an opening 22 into the fuse-box which, as illustrated, carries afuseblock 23 of which only the barriers I extend through from the backof the box, thereby leaving no wires expose i where they may becontacted by one screwing a fuse into the shell 8. In the arrangementshown, there are four fuse-blocks each having its indicating lamp l3positioned in theopening provided in said barriers.

It will be noted that in all the constructions described, the openingsto receive the lamp bulbs l3 have no sockets therein, and it istherefore not necessary to provide any base for the bulbs I3, the samebeing held in the openings Hrby the same kind of cement or wax used incovering the impedances and circuit terminals.

In Figure 9, I have shown a diagrammatic arrangement wherein the currentsupply wires 24, and 25 are connected through the fuses 26 and 21 to theload circuit 28. Each of the fuses 26 and 21 is shunted by a bulb l 3and impedance l8 con-' nected in series therein around the fuse.

Assuming that the load switch 29 is closed and something happens. in theload circuit to blow one of the fuses 26 or 21, its associated bulb willimmediately become lighted-and stay lighted until the fuse has beenreplaced, and the location of the bulb l3 on the fuse-block, as has beendescribed, will clearly indicate the fuse that has blown.

Should for any reason the load switch 29 be open, then either of thefuses 26 or 21 might be in an inoperative state and. give no indicationof this condition. Therefore, to overcome this point which might beconsidered a disadvantage, I have provided an auxiliary impedance 30which may be permanently connected across the ends of the fuse terminalsID to which the load circuit is connected. The impedance may be acondenser 33, as shown in Figure 10, or a very high resistor 30, asshown in Figure 9, of the order of one megohm so that the weak currentthrough this, even with the switch 29 open, is very nearlyinfinitesimal; that is to say, if a large number of these were connectedacross different circuits all being supplied through one meter, theleakage In case the switch 3| is used, this may be closed' while anobservation test is being made on the fuses and then opened. In fact,the switch may be of a type that will open automatically after theclosing force thereon has been removed.

What I claim is:

1. A fuse-block having barriers forming pockets for contact members toreceive fuse terminals, :said block having at least one. opening thereinlocated in one of said barriers, the opening breaking through itsbarrier into one of said pockets, 9. small neon gas, or the like, filledbulb positioned in said opening, at least one very high impedancelocated in a recess in the block and connected in series with said bulb,the two being permanently connected in shunt across said fuse contactmembers. I

2. Condition indicating means for a fuse including a fuse-block ofinsulating material and of standard dimensions having at least onepocket with contact members therein to be engaged by fuse terminals; abarrier adjacent said pocket; said block.havingat least one openingtherein on the fuse side thereof closely adjacent said pocket and insaid barrier, a small gas-filled bulb having spaced electrodes locatedin said opening, at least one very high impedance located in a recess inthe block on the rear side thereof adjacent said bulb opening, the bulband impedance being connected in series and across said fuse contactmembers, and in shunt to a fuse when in operative position in thefuse-block.

3. Condition indicating means for a-fuse as set forth in claim 2,characterized in that said opening for the bulb breaks into said pocketand the bulb is held in place within said opening by similar sealingcompound as used in the assembly of the contact and associated terminalmembers used in the block and in protecting said impedance.

4. Condition indicating means for a fuse'including a fuse-block ofinsulating material and of standard dimensions having at least onepocket with cbntact members therein to be engaged by fuse terminals; abarrier adjacent said pocket; said block having at least one openingtherein on the fuse side thereof closely adjacent said pocket and insaid barrier, a small gas-filled bulb having spaced electrodes locatedin said opening, at least one very high impedance located in a recess inthe block on the rear side thereof adjacentsaid bulb opening, the bulband impedance being connected in series and across said fuse contactmembers, and in shunt to a fuse when in operative position in thefuse-block, and a further high impedance bridged across a pair of fuseterminals of opposite polarity at the load side thereof.

5. Condition indicating means for a fuse including a fuse-block ofinsulating material and of standard dimensions having at least onepocket with contact members therein to be engaged by fuse terminals; abarrier adjacent said pocket; said block having at least one openingtherein on the fuse side thereof closely adjacent said pocket and insaid barrier, a small gas-filled bulb having spaced electrodes locatedin said opening, at least one very high impedance iccated in a recess inthe block on the rear side thereof adjacent said bulb opening, the bulband impedance being connected in series and across said fuse contactmembers. and in shunt to a fuse when in operative position in thefuse-block, a further high impedance bridged across a pair of fuseterminals of opposite polarity at the load side thereof, and a switchfor controlling this lastmentioned impedance circuit.

6. A fuse-block having a contact member on one side thereof to receive afuse, also an opening on the same side and having therein a gasglow lampwith spaced electrodes and on the opposite side of said block at leastone recess to receive a circuit contact member, and a high impedanceelement which is connected in series with the lamp and across itsassociated fuse and further characterized in that a high impedance isadapted to be connected across a pair of fuses of opposite polarity atthe load side thereof.

7. In the combination of a fuse and gas-filled bulb having spacedelectrodes connected in shunt thereto, means for insuring that the bulbwill give an indication when the fuse opens, said means including a veryhigh impedance connected across the fuse or fuses in a given circuit onthe load side thereof.

8. A fuse-block having on one side thereof barriers forming pockets forcontact members to receive fuse terminals, and on the other side,channels for contact members and certain impedances, said block havingan opening adjacent each pocket and located in a side barrier for saidpocket, a gas-filled bulb positioned in each of said openings, at leastone very high impedance for each bulb located in one of said channelsand connected in series with its associated bulb, the two beingpermanently connected in shunt across said fuse contact members.

9. A fuse-block of the type set forth in claim 8, further characterizedin that the block is of standard commercial dimensions and the fuses tobe used in the block are also of standard commercial construction, sizeand shape.

- 10. A fuse-block as set forth in claim 8, further characterized inthat a further'high impedance is bridged across a pair of fuse terminalsof opposite polarity at the load side thereof.

11. A fuse-block having on one side thereof contact members to receive afuse or fuses of standard commercial construction, size and shape, saidfuse-block having openings therein adjacent each fuse, a gas-filled bulbpositioned in each of said openings and at least one high impedance foreach bulb positioned within a space provided in the block and connectedin series with its associated bulb, the two being permanently connectedin shunt across said fuse contact members.

12. A fuse block as set forth in claim 11, further characterized in thatthe block as well as the fuses are of standard commercial construction,size and shape.

13. A fuse block as set forth in claim 11, further characterized in thata further high impedance is bridged across a pair of fuse terminals ofopposite polarity at the load side thereof.

14. A fuse block as set forth in claim 11, further characterized in thatthe block as well as the fuses are of standard commercial construction,size and shape, and further characterized in that a further highimpedance is bridged across a pair of fuse terminals of oppositepolarity at the load side thereof. v 1 15. In a system of the type whichincludes electrical supply buses and branches therefrom in which thermalfuses are inserted in each leg of a branch and indicator lamps areconnected in shunt of the fuse links, the combination of meanspermanently connected between the two legs of a branch whereby a path isafforded for current flow for lighting one or both of the indicatorlamps.

16. In a fuse block of the type in which means are provided forreceiving two electrical supply conductors and terminals for connectinga branch circuit from said conductors in which a fusible link isconnected between each electrical supply conductor and each leg of thebranch circuit, the combination of means connected between saidterminals affording a current path whereby when fusible links areinserted between each leg of the branch circuit and the supplyconductors and are shunted by indicator lamps, the said indicator lampsmay be illuminated even when no other path exists for current flowbetween the conductors of said branch.

17. In a fuse block of the type providing for connection with supplymains and providing terminals for a branch circuit with receptacles forthe insertion of plugs provided with fuses, and with'indicator lamps inshunt with said fuses, the combination of a resistance connected acrosssaid terminals for insuring the tion of the indicator lamps, uponfailure of any or all of said fuses.

18. In a. system of the type which includes electrical supply buses andbranches therefrom in which thermal fuses are inserted in each leg of abranch and in which indicator lamps are connected in shunt of the fuselinks, and responsive automatically each upon failure of one of saidfuse links, the combination of means permanently connected between thetwo legs of a branch whereby a path is afforded for lighting one or bothof the indicator lamps upon failure of either or both of said fuselinks.

19. In a fuse block of the type providing for connection with supplymains and providing terminals for a branch circuit with receptacles forthe insertion of plugs provided with fuses, and with indicator lamps inshunt with said fuses, the combination of a condenser connected acrosssaid terminals for insuring the certainty of illumination of theindicator or all of said fuses.

lamps, upon failure of any LEON S. BRACH-

